Inductively coupled power, useful for wireless elevator hall fixtures

ABSTRACT

Fixtures ( 27 ) at a doorway of a landing are formed integrally with a frame ( 17 ). Power is provided by an inductive coupler ( 32 ) having a core ( 70 ) and primary ( 75 ). The core is thin ferrite and extend significantly beyond the coils in the plane the coils are wound, to provide en extremely low resistance path for the efficient transfer of AC power.

TECHNICAL FIELD

This invention relates to inductive power coupling, useful, forinstance, for powering elevator hall fixtures, including call buttonlights, directional lanterns, and floors indicators, for the purpose ofelimination of building wiring. Wireless power is supplied to the hallfixtures by inductive coupling of power from the elevator while it is atthe landing.

BACKGROUND ART

Elevator systems have hallway fixtures at each floor, includingdirectional lanterns, hall call buttons, and in some cases, elevatorposition indicators. Traditionally, each hallway fixture on every floorwas powered by means of wires run through the hoistway, with additionalwires to provide signal communication between the floor and thecontroller, which has typically been located at the top of the hoistwayin a machine room. To reduce the amount of wiring, modern systems useserial communication buses, which typically may require two wires forcommunication and two for power, one bus each for the lanterns and callbuttons. The wiring requires significant installation time in newbuildings, and makes modernization of existing elevators extremelydifficult. Further, work in the hoistway is dangerous and should beavoided if possible.

The communication aspect of hall fixtures has been rendered wireless bymeans of radio frequency (or other) wireless communications. However,power is still required to be provided by wires, which must bespecifically installed in the building during initial construction of anelevator system, or as a consequence of modernization.

Suggestions have been made to use very large coils disposed on theelevator car and the hoistway wall with large air gaps, such as the 30mm (1.2 inch) running clearance between moving and stationary portionsof an elevator system, which is required by typical regulatory codes, sothat power can be inductively coupled from the car to the hoistway wallwhen the elevator car is at a landing, thereby to power the fixtures. Ithas also been suggested that magnetic coupling of power, such as betweenan elevator car and a hoistway wall, may be effectively achieved withcoils having large C-shaped cores. However, it has been determined thatlarge coils and C-shaped cores, with large air gaps, cannot effectivelytransfer the necessary power in a compact and efficient manner.

DISCLOSURE OF INVENTION

Objects of the invention include: an improved magnetic coupling forcontactless power transfer; provision of improved contactless electricpower transfer; provision of improved power transfer for wirelesselevator hallway fixtures; and provision of improved power coupling forelevator hallway fixtures which receive power without building wiring.

This invention is predicated on our discovery that efficient,contactless inductive coupling for power transfer is effected by meansof ferrite cores which are very much larger than the windings so as toprovide a large area of magnetic coupling between a primary winding anda secondary winding.

According to the present invention, a magnetic power coupling comprisesa large, low reluctance path through a required air-gap, such as, forinstance, elevator/hoistway clearance, with a minimum of ferritematerial, thereby saving costs and space and reducing the volt/amprequirements of driving electronics. A primary and a secondary bothinclude a ferrite core with a winding wound onto the ferrite core, saidferrite cores being surrounded by said windings along the length of saidwindings and over a portion of the width of said windings, said ferritecores having a length which is at least as great as the length of saidwinding, said ferrite cores having a length and width which is betweentwo and ten times as great as the air-gap between the primary andsecondary. According to the invention further, an inductive powercoupling apparatus includes coupling high frequency electric power(e.g., tens of kilohertz), which may, for instance, be provided by anH-bridge in turn driven by DC power obtained by rectifying ordinarybuilding line voltage, all of which form a high frequency AC source. Onthe secondary side, the received high frequency signal is simplyrectified and used to charge a battery, which supplies the power to thefixtures as needed.

According further to the invention, power for elevator hall fixtures isprovided by magnetic coupling with a source on an elevator car.

The invention provides a power coupling capability useful in a widevariety of applications; for instance, it obviates the need for anypower wiring whatsoever at an installation of elevator hallway fixtures.

Other objects, features and advantages of the present invention willbecome more apparent in the light of the following detailed descriptionof exemplary embodiments thereof, as illustrated in the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view of an elevator hall door frame havingfixtures and employing a magnetic coupling as a source of power, inaccordance with the invention.

FIG. 2 is a rear elevation view of the hallway door frame of FIG. 1.

FIG. 3 is a partial, partially sectioned, top view of the door frame ofFIG. 1 and an elevator car.

FIG. 4 is a perspective view of a magnetic coupling of the invention.

MODE(S) FOR CARRYING OUT THE INVENTION

Powering elevator hallway fixtures is one example of use of theinvention.

Referring to FIG. 1, a doorway 13 at a landing 14 of an elevatorincludes a hoistway door opening 16 defined by a door frame 17. Theopening 16 is closed off by hoistway doors 19, 20 except when a car isservicing the landing 14 (which means stopped and opening the doors).The door frame includes a call module 22 which has one or two hall callbuttons, in the conventional fashion such as an up call button 23 and adown call button 24. The call buttons may be illuminated by LEDs, or insome other suitable way, to indicate that a call has been registered.The door frame 17 also includes a lantern fixture 27 having one or twoconventional directional arrows, such as an up directional arrow 28 anda down directional arrow 29 that are selectively illuminated to indicatethe direction of elevator travel. The arrows may be illuminated byhigh-intensity LEDs, or in some other suitable way, to indicate cardirection.

The fixtures 22, 27 are powered by the inductive coupler 32 of theinvention, which is seen more clearly in FIG. 2.

In FIG. 2, the inductive coupler secondary 70 is shown connected by acable 50 to the lantern fixture 27, which is connected to the callfixture 22 by a cable 51. The cables 50, 51 are within the frame 17. Thelantern fixture 27 may have an electronic module 54 and an energystorage device, which may be a battery 55 or a super capacitor, all asis known in the art. The electronic modules will include circuits forreceiving the high frequency current from the inductive couplersecondary 32, rectifying it, and using the power to charge the battery55, all as is known and within the skill of the art. The electronicmodule 54 may also include communicating with the elevator controller,such as by radio frequency electromagnetic radiation, monitoring theremaining power of the battery 55, as well as controlling theapplication of power to the directional lights 28, 29 and to the up anddown hall call buttons 23, 24. The module 54 may take the form ofpiconet modules, disclosed in commonly owned, copending patentapplication PCT/US02/32848, which may comprise modules conforming toBLUETOOTH specifications, utilized in the manner described in thatapplication. Other electronic modules, which can operate with extremelow power consumption and provide adequate control and communication maybe utilized, as desired.

The efficient inductive coupler secondary 70 has few turns of wire 71but a very large ferrite core 72, as shown in FIGS. 3 and 4. On theelevator car, an inductive coupler primary 75, similar to the couplersecondary 70, receives high frequency power (e.g., about 20 kHz) from anH-bridge 80. The H-bridge 80 operates on DC power provided by arectifier 82 in response to conventional AC line voltage 83, as is knownin the art; H-Bridge 80 frequency is set by oscillator 81.

Referring to FIG. 4, the secondary 75 of the coupler 32 has a primarywinding 86 wrapped around a core 87, both of which can be identical tothe winding 71 and core 72 of the secondary 70. However, to decrease theAC and DC resistance in the primary winding 86, it may comprise twice asmany wires or more of the same size as the secondary coil 71, driven inparallel.

To avoid losses to adjacent structures having magnetic reluctance, theprimary and secondary have shields 84, 85, at least as large as thecores 72, 87, of aluminum or other non-magnetic material. There may beair-gaps between the shields and respective cores.

The cores 70, 75 are ferrite so as to provide minimum reluctance to themagnetic field, thereby increasing the efficiency with which power canbe transferred from the primary to the secondary.

The width and length of the core, dimensions L and W, should be from 2to 10 times the required air gap S.

The thickness, T, of the cores should be sufficiently large to keep thecore from saturating or overheating. Increasing the cross-sectional areagiven by the core thickness, T, times the core length, L, reduces bothsaturation and overheating potential. However, L should be increased inpreference to T so as to maximize the effective cross section of themagnetic circuit air gap. Thus, the thickness, T, of the cores is keptrelatively small, less than 25% the width and more favorably nearer to5%. Extremely thin cores, less 5% of the width, could be used but wouldlikely present manufacturing difficulties. The exact thickness is drivenby the material properties of the particular ferrite used. Examples are:

-   -   width (W) between 60 and 300 mm;    -   length (L) between 60 and 300 mm;    -   thickness (I) between 3 and 30 mm.

The length, L, of each core 70, 75 is selected to accommodate the lengthof the primary and secondary coils 71, 86; however, the cores could haveextensions on either side of the coil, in some cases, in order toincrease coupling, if desired.

1. An inductive power coupler, comprising: a primary; a secondaryseparated from said primary by an air-gap; said primary and secondaryeach having a thin ferrite core with a coil wrapped around the core;each of said cores having a width extending outwardly from thecorresponding coil, said width and a length of said cores being betweentwo and ten times as large as said air-gap, and a thickness of 5% -25%of said width.
 2. A magnetic power coupler according to claim 1 whereinsaid primary and secondary are separated by a gap of on the order of25-35 millimeters (1-1.4 inch).
 3. A magnetic power coupler according toclaim 1 wherein: said thickness is between 3 millimeters (0.12 inch) and30 millimeters (1.2 inch); said length is on the order of 60 millimeters(2.4 inch) to 300 millimeters (12 inches); and said width is on theorder of between 60 millimeters (2.4 inch) and 300 millimeters (12inches).